(154g) Synthesis of Ethyl Diazoacetate in Microchemical System

The EDA synthesis using ethyl glycinate hydrochloride (EGH) and sodium nitrite (SN) as starting materials involves with diazo reaction for EDA generation (main reaction) and EDA decomposition reaction (side reaction). In this work, assuming that the main reaction is much faster than the side reaction, we determined the side reaction kinetics and the reaction heats of the side reaction and the main reaction by processing the calorimetric data in segmentation. The H_SR, H_MR, and E_a,SR were 93.1 kJ/mol, 209 kJ/mol, and 72.5 kJ/mol, respectively. And then, establishing an adiabatic microchemical system with in-situ infrared temperature measuring accessories, we acquired the time profile of adiabatic temperature rise by the switch between the spatial dimension and time dimension. Considering the adiabatic temperature rise comes from main reaction as the residence time being short enough, we simplified thermodynamics equations as well as reaction kinetics equation, and derived the kinetics equation of main reaction by a multi-parameter numerical computational regressive analysis using Monte Carlo method. The E_a,SR was 39.2 kJ/mol. The comparison of main reaction kinetic equation and side reaction kinetic equation confirms the feasibility of assumptions for methods design. Combining the kinetic equations of main reaction and side reaction, the continuous EDA synthesis process in an adiabatic microchemcial system could be strictly modelled. It could predict the experimental results well, and also be exploited for initial reaction conditions optimization. When SN is three times in excess, pH about 4.1, and T₀ around room temperature, it is facile for achieving an effectively continuous EDA synthesis using an adiabatic microchemical system. Compared with semi-batched industrial process, the EDA yield could increase from 85 % to 95 %, the residence time decreases from several hours to tens of seconds. This new EDA synthesis may have good potential in practice due to compromising the reation efficiency, selectivity, and yield.